Settling tank



March 7, 1961 A. L. GENTER ETAL 7 66 SETTLING TANK 3 Sheets-Sheet 1Filed May 14, 1959 M f v H H x q .qiliilln T i i H i FIG.2.

ATTORNEYS March 7, 1961 A. L. GENTER ETAL 2,973,866

SETTLING TANK Filed May 14, 1959 3 Sheets-Sheet 2 F'LUID LEVEL I6 I 7 I424 r1) 2 IO/ an FIG.5. o

INVENTORS ALBERT L. GENIER RICHARD R.KENNED.Y ROBERT M. K ENNEDYATTORNEYS March 7, 1961 A. 1 GENTER ETAL 2,973,866

SETTLING TANK Filed May 14, 1959 s Sheets-Sheet s DIRECTION OF FLOW -ea7 U W w INVENTORS ALBERT L. GENTER RICHARD R.KENNEDY ROBERT M. KENNEDYBY 6 Z vM ATTORNEYS States Pate Unite SETTLING TANK Filed May 14, 1959,Ser. No. 813,231

14 Claims. (Cl. 210-519) This invention relates to an apparatus forseparating dispersed solids from a carrier liquid. The apparatus of thisinvention finds particular, utility when operated as a settling tank forthe treatment of sewage, and the ap paratus is particularly concernedwith the manner in which the solids content of sewage is separated fromthe liquid content.

As is apparent from a review of the art, in all settling tanks there isa circulating liquid from which dispersed particles are to be separated.Forseparation by settling velocity of the smallest particle must exceedthe velocity of anyrising liquid which may act upon that particle eitherdirectly or indirectly. At the same time, for efiicient operation, theoverflow rate of the tank must be maintained at a high level foreflicient operation,

Prior to this invention, it was believed that the only efficient Way tomeet the required velocity relation be tween rising liquid and settlingparticles was to use a tank of the well-known multi-tray? typeconstruction. Such tanks had at least one severe disadvantage. Theeverpresent bacterial action in and on sewage solids could not becontrolled. As a result, the multi-tray devices-became foulsmellingunder the action of the anerobic bacteria and requiredcontinuous cleaning Notonly were operating costs increased, butefficiency was greatly reduced due to the time involved in cleaningshut-downs. It was known that elongated tanks are not subject to thesevere disadvantage of the multi-tray type devices because inrectangular units the bacterial action can be controlled, but heretoforethe required relation between velocities could not efficiently beachieved. I

In prior rectangular or elongated tanks, the overflow rate necessarilywas maintained at a low level in order to prevent the velocity of risingliquids from exceeding the velocity of the small particles to besettled. Thus, although elongated tanks were desirable from a bacteriacontrol standpoint, their operation was inefiicient because wheneverhigh overflow rates were maintained, small particles could not beseparated from the carrier. liquid.

The first primary object of this invention is to provide an efficientrectangular or elongated settling tank, that is, one in which thesettling'velocity of small particles 76X- ceeds the velocity of risingcirculating liquids when high overflow rates are maintained.

Aside from the overflow rate and velocity considerations which mustenter into settling tank design, the inlet design is of particularimportance. For proper settling of particles from a carrier liquid, itis necessary to provide a laminar or sheet flow of the carrier over thesurfaces on which the particles are to be settled. At the same time, theinlet cannot be so constructed as to be suscepany level 'within thetank. The laminar or sheet flow exiting-from the inlet must be confinedto a shallow depth, to minimize the distance a particle to be settledmust travel and the surfaces on which settling is to take t. V V i g r EPatented Mar. 7, 1961 2 place should be as large as possible so as togive maxi mum surface area for intercepting descending particles. Thesecond primary object of this invention is to provide a settling tank ofelongated construction in which-the settling surfaces are of maximumarea, and the inlet construction is such as to cause the incoming liquidcarrying dispersed particles to assume a shallow laminar flow over thesettling surfaces. 7

In order to achieve maximum settling surface area, it has heretoforebeen suggested that baffies be used within the settling tank. However,two factors have been neg-' lected in such suggestions, namely, thedirection and angle of slope of the bafile, and the depth relation ofthe battle surfaces to the laminar flow. Accordingly, the third primaryobject of this invention is to provide a rectangular settling tank inwhich the battle arrangement is disposed with respect to the inletdevice so as to render the most efficient settling of particles carriedby incoming carrier liquid.

in addition to proving a settling tank as described above, the inventionprovides for an improved means for carrying separated particles orsludge from the settling surfaces to the sludge outlet chamber of thetank. Specifically, the invention provides for a fully submerged sludgeconveyor which acts in conjunction with the other components of theimproved tank to increase etficiency.

Although the general primary objects of the invention have been setforth above, specific objects of this invention are important. One ofthe specific objects of this invention is to provide an inlet meanswhich comprises a series of Ts so disposed as to cause the velocity ofincoming liquid to be reduced substantially by the counter action ofstreams of incoming liquid upon one another. A still further specificobject of this invention is to provide a settling tank having the abovedescribed features, and in addition a series of bafiles disposed so asto lean away from the-inlet distributors at an adjustable angle lessthan the angle of repose of the solids settling from incoming carrierliquid.

It is important that the collection of solids on any settling'surface bekept as thin as possible so that trapped liquid between the particlesmay easily escape, and therefore, a further specific object of thisinvention is to provide a rectangular settling tank in accordance withthe the settling surfaces free of slime deposits, sludge deposits, orany over-accumulations.

Still further specific objects of this invention are'to provide arectangular settling tank in accordance with the above objects, and: (1)having a ribbon and/or cutflight conveyor for transporting sludge to theoutlet chamber of the tank so as to easily handle the stickyaccumulations of settled particles, (2) having a clear liquid overflowcollecting launder at the overflow end of t the tank, to provide foreven overflow, (3) having me chanical means tovary the inclination orslope of the baffles within the tank, (4) having hydraulicallylubricated supporting bearings for the sludge conveying means soar, toprevent bearing failure or clogging and (5) hav- V particles ina carrierliquid from-the carrier. Accordtible of easy clogging, and cannot belocated merely at; t

tank. Basically, the invention provides forfeeding sew- O age composedof dispersed particles in a carrier liquid into a settling tank,directing the carrier into separate streams entering the tank inopposing relation whereby the carrier begins travel through the tank asa nonturbulent laminar flow, allowing the carrier to flow through thetank at a rate which allows the dispersed solids therein to settletherefrom, intercepting said particles as they settle from said carrieron inclined surfaces, moving the inclined surfaces to hasten movement ofthe particles to the bottom of the tank, and conveying the particlescollected on the surfaces to a single outlet location.

As should be apparent from the above general discussion of the state ofthe art, and objects of the invention, the apparatus provided by theinvention basically comprises an elongated tank, inlet means within saidtank for directing an incoming liquid carrier into opposing streams, aseries of bafiies within said tank leaning away from said inlet means atan angle equal to or less than the angle of repose of particles carriedby said incoming liquid carrier, conveying means under said bafiies forconveying the particles collected on said bafiies to the sludge outletend of said tank, and means for moving said 'oafiles to hasten movementof particles deposited thereon toward the bottom of said bafiles and tosaid conveying means.

Objects other than those specifically set forth above, will becomeapparent from the following detailed description of illustrativeembodiments of the invention. The illustrative embodiments are bestunderstood if the description is considered with the annexed drawings,wherein Figure 1 is a plan view of an improved settling tank constructedin accordance with the teachings of this invention.

Figure 2 is a cross-sectional view of the tank shown in Figure 1, butshowing in addition details of construction of means for agitating thebatfie structure and means for conveying settled sludge to an outletchannel.

Figure 3 is a fragmental View of the tank shown in Figure l, butpresenting a modified form of inlet distributor constructed inaccordance with the teachings of this invention.

Figure 4 is a cross-sectional view of the tank shown in Figures 1 and 2,but presenting a modified form of halide structure provided by thisinvention.

Figure 5 is a cross-sectional view of a multiple tank arrangementconstructed in accordance with the teachings of this invention.

Figure 6 is a side cross-sectional view of an improved settling tankprovided by this invention and having a vibratable bathe unit.

Figure 7 is a cross-sectional view of the tank shown in Figure 6, Figure7 having been taken on line 77 of Figure 6.

Figure 8 is a fragmental detailed view of the baffle-slot arrangementshown in Figure 2.

Figure 9 is a cross-sectional view of a bearing structure which ispreferably used in tanks constructed under the teachings of thisinvention.

Figure 10 is a fragmental detailed view of an overflow launder adjustingmeans.

In the drawings, the numeral 2 has been used to generally designate arectangular or elongated settling tank constructed in accordance withthe teachings of this invention. By referring to Figure 1 it will beseen that an inlet conduit 4 and an over-flow outlet conduit 6communicate with the interior of the tank 2. Sewage consisting of acarrier liquid with dispersed particles therein, or other mixtures ofsettleable solids suspended in liquids, enters a trough 8 disposed atthe inlet end 10 of tank 2, and pass from trough 8 into the centralportion of the tank through a series of inlet. distributors 12, 12(a),12(b), and 12(c).

' The preferred design of the distributors is shown in Figure 1. Theyhave a T shape and are disposed in a horizontal row such that streams ofliquid exiting from adjacent ends of successive distributors meet oneanother head on. For example, the stream of unsettled mixtures leavingend X of distributor 12 directly meets the stream of mixtures leavingend Y distributor 12(a). The two streams inlet velocities are in directopposition and as a result, the inlet velocity of one stream cancels theinlet velocity of the other stream so that the liquid introduced intothe tank through the adjacent ends of the successive conduits hassubstantially no inlet velocity. Because of this, the liquid assumes asubstantially non-turbulent sheet or laminar flow through the tank.

End Y of distributor 12 and end X of distributor 12(c) are disposedadjacent the side walls 14 and 16 of tank 2, and the streams of incomingsewage exiting from these two ends of the distributors hit the sidewalls. The side walls act as baffles to slow down and distribute the endstreams.

The T distributors are obviously tubular structures, and they may haveany diameter which seems suitable. They eliminate the need for thewidely used perforated inlet plates which are easily clogged. Althoughfour inlet distributors are shown in Figure 1, it should be understoodthat any number may be used.

In Figure 3, an alternate form of inlet distributor is presented. Byreferring to this figure, it will be noted that the T distributors ofFigure 1 have been replaced by straight pipes 18, 18(a), 18(b) and 18(0)and bailie plates 20, 20(a), 20(b) and 20(0). With this type ofdistributor, the velocity of incoming sewage streams is materiallyreduced when the streams hit against the battles, and the flow of sewagepassing from the baffles is substantially a non-turbulent laminar flow.The action is similar to that achieved with the T distributors of Figurel. Streams hitting the bafiles initially are slowed down, but spreadlaterally and meet head on with streams spreading from adjacent bafilesso that inlet velocities are in direct opposition. This results insubstantially cancelling the inlet velocities so that all incomingsewage assumes non-turbulent sheet flow.

Notwithstanding the fact that the inlet distributor arrangements shownin Figures 1 and 2 are preferable, any inlet distributing means may beused which insures substantial elimination of the energy of sewageintroduced into the tank and which is not easily rendered inoperative byclogging.

Unsettled mix which leaves the inlet distributing means, and has assumeda non-turbulent laminar flow, passes to the tank sedimentation zone 22.Disposed within zone 22 are a plurality of baffles 24 which are held inplace preferably in channeled grooves 26 on the side walls 14 and 16 ofthe tank. As shown in Figure 2, the grooves are V-shaped, and thebottoms of the baffles may be hinged at their lower end so that thebaffles may be moved from a position adjacent one leg of the Vs to aposition adjacent the other leg of the VS. Of course, any constructionother than V-shape may be used if desired.

The movement of the baffles is more clearly presented in Figure 8 whereone leg. of V groove 26 is designated as P and the other leg isdesignated as Q. Bathe 24 as shown is pivotally connected by means ofrod 23 to either side wall of the tank, and the bafile obviously can bemoved from a position where it abuts leg P to a position where it abutsleg Q of the groove 26. The pivotal connection by means of rod 28 ismerely exemplary, and it should be understood that any pivotalconnection may be used. In fact, in some instan es it may be desirableto make no secure pivotal connection, and allow the baflies merely torest in the bottoms of the V groove 26.

The bafiles 24 may be solid sheets, as shown in Figures 1, 2 and 8, orthey may comprise a series of interconnected strips. asshown in Figure4. Regardless of the bafile construction, according to the preferredembodiment of the invention, the bafiles may be all linked to a bar orrod 27 which extends lengthwise through the tank 2 and is preferablydisposed above the liquid level in the tank. If bar 27 is reciprocated,the bafiies will reciprocate with it so that the angle or slope of thebafile can be adjusted to any angle desired. Moreover, if bar or rod 27is periodically reciprocated, the bafiles are periodically moved, andany material which has settled thereon is shaken loose. This is animportant feature of this invention, as will be explained more fullyhereinafter.

In Figure 2 an exemplary mechanical means for reciprocating rod 27 andthereby baffles 24 is designated generally by numeral 30. The mechanicalmeans comprises a ratchet gear 32 secured to a shaft 34 which may bedriven by a motor (not shown) through suitable gearing (not shown) ordirectly. A lever 37 pivoted about point 35 and coupled to rod 27 bearsagainst the teeth on ratchet gear 32. The lever 37 is biased toward theratchet gear by spring 38 so that as the extremities of the ratchetteeth pass the end of lever 37 bearing thereagainst, the lever is pulledin. As is apparent, the ratchet teeth cause reciprocation of rod 27 andbaffles 24.

A modified form of baffle structure provided by the invention is shownin Figures 6 and 7 wherein it will be noted that the bafiles 24 aresupported by a frame 40. The frame has side extensions 42 which areadapted to rest upon walls 14 and 16 of tank 2. Between the extensionsand the protrusions, there is disposed a resilient pad 43 so that thewhole frame including the baffles may be vibrated within the tank. Avibrator 44 which may be either electrical or mechanical, or acombination of both, is carried on the frame and functions to agitatethe baflies in a similar manner to the mechanical ratchet means 30.

The baffles 24 may be rigidly secured to the frame 40 by any appropriatemeans, e.g., welding, screws, or the like or they may be pivotallycoupled to the frame in slots so that their inclination or slope can bevaried.

It should be understood that the particular method of securing thebaffies in place forms no part of this invention. However, the provisionof the baffle structure, and the provision of some means for agitatingthe bafiles are essential features of this invention.

The disposition of the baffles and relation between the baffles and theinlet distributors is also of critical importance. In all modificationsof the invention the bafiies 24 slope away in the direction of thelaminar flow, that is, with the top edges of the baflies leaning awayfrom the inlet distributors, or toward the rear edge 50 of tank 2. Theangle of inclination of these bafiles should be 20, or less than thenatural slope or angle of repose assumed by the granular or semi-fluidmaterial settling out of the mixture and onto the inclined surfaces 24.

The angle of inclination of the baffles must be comparatively small,that is, less than 20 because for eflicient operation the angle must beless than the angle of repose of solids settling on the baffies. It isdifiicult to specify the exact angle by formulation, and the importantfactor is that the baffles slope away from the inlet distributors.

The direction of flow of liquid through the settling tank is shown byarrows in Figure 2. It will be noted that the material settles out ofthe laminar fiow at the top of the .tank and on to the inclined bafflesurface. Naturally the settling material carries with it a certainamount of liquid. As the settling material hits the bafile, it beginsthe glide down the bafile and the speed of the travel of the settledmaterial down the baffle may be periodically or continually augmented bythe mechanical agitation of the baffles as pointed out above. Theinclination of the bafiies naturally increases the settling capacity ofthe tank because with inclined batfies the thickness of the layer ofsettling solids on the battle is at all times relatively thin. Thus,water or other liquid which is to be separated from the settled materialonly need pass through a thin layer of solids in order to become part ofthe circulating liquids. To express this another way, the number ofsurface pores available for egress of water is increased by incliningthe baffles.

By referring to Figures 2 and 6 particularly, it will be noted that theinlet distributors 12, 12(a), 12(b) and 12(0) are disposed insubstantially the same horizontal plane as the disposition of thebaffies 24. Because of this relationship the laminar flow issuing fromthe inlet distributors is in juxtaposition to the top of the bafiles sothat settling material need travel a minimum distance before beingintercepted by a baffle surface.

As the material which has settled out of the incoming sewage slides downthe baffle water is expelled therefrom as suggested above, and theexpelled water passes upwardly against the undersurface of the precedingbaflie. The settled material upon leaving the bottom of the bafflesdrops onto a sludge conveying unit 75. The conveying unit comprises ashaft 77 which extends lengthwise through the settling tank and isdriven by a motor 79 through a suitable pulley or gear arrangement 81.The shaft 77- carries a screw or ribbon conveyor 83. The speed at whichthe shaft and thereby the conveyor is driven is dependent on the speedof the motor 79, and preferably the motor is of the variable speed typeso that conveying of the sludge at'the bottom of the tank may beperformed at any desired rate. The shaft 77 is preferably mounted instuffing glands of the type shown in Figure 9. These glands comprise ahousing which contains a soft rubber bearing 182 having molded helicalgrooves therein. Water is introduced under pressure through an inletpipe so that the helical grooves are constantly filled with a fluidunder pressure. This type of bearing prevents clogging and wear andinsures continuous operation of the conveyor.

As will be seen by reference to Figures 2 and 6 a sludge outlet channel90 is provided at thebottom of the front of the tank and the conveyor 75delivers sludge to the channel. The conveyor may have larger screwblades toward its forward end to more efiicientlycarry the heavierquantities of sludge, or as shown in Figure 6 paddle blades may beprovided adjacent the sludge outlet channel in order to thereby mix theheavy sludge previous to its discharge from the settling tank via outletpipe 120.

It should be pointed out that the conveyor should be either of theribbon o-r cut-flight type sinceboth of these types of conveyors areparticularly adapted to convey sticky material. A solid flight conveyortendsto tunnel through such material without moving it. The preferredembodiment of the invention providesfor utilizing the ribbon conveyorsince this type most efiiciently transports the'settled solids.

In addition to the components of the settling type tank 1 provided byhis invention, it should be pointed out that overflow launders, ortroughs 139 are disposed at the'i rear of the settling tank near the topliquid level so that the clear liquid to be drained from the tankoverflows evenly. As shown in Figure 1, one of each of the laundersflows into an overflow collecting chamber 135.

In the foregoing description, the operation and comif the rod 27 ismoved forward from the position shown I V the top of the bafiles willrise. Thus, the rod 27 not only allows for adjustment of the baffleangle, but it;

also allows for adjusting the depth which particles must travel tosettle from theincorning laminar flow. The overall construction of thesettling tank is of primary importance because it allows for settlingeven very small particles at high overflow rates. The provisionofinclined baifles at an angle less than the angle of repose of thesolids to be settled, and the provision of means to agitate the bafflesnecessarily speeds up'the settling out operation, and a speed-up in thesettling out operation allows for flowing a greater quantity of sewagethrough the tank per unit time. Thus, the overflow rate can be increasedwhen the improved tank provided by this invention is used.

The particular materials from which the components of the settling tankare constructed are not factors of this invention, but it should beunderstood that the materials should be of types which do not reactchemically with the components of the sewage to be treated.

Although the coupling between baffles 24 and rod 27 has been describedonly generally above, it should be apparent from Figure 2 that each baflle carries an extension 25 on one side thereof, which extension issuitably coupled (by bolt, or weld, or the like) to rod 27. Similarly,lever 37 is suitably coupled to rod 27 by any equivalent means. Theextensions 25 are out of the way of the flow when disposed on the sidesof the battles, and thus do not render the flow turbulent.

A bracket means 89 may be utilized for supporting the conveyor shaft 77as shown in Figures 4 and 7. The bracket means gives the shaft supportin addition to that which it receives from the bearings lit (Figures 2.and 9). Bearings similar to those designated by numeral 110 may be usedin the bracket means 89 to insure flawless operation. As shown, thebracket means is generally T-shaped, and has extensions 89' which fitagainst the walls of tank 2.

The walls of the tank slope toward one another as shown, and the angleof slope preferably is less than the angle of repose of the particles tobe settled. In fact, best results are obtained when the angle of slopeof the side walls is substantially equal to the angle of slope of thebaflles. Since the batfles may be agitated through a small angle, theangle of slope of the side walls can only be exactly equal to the angleof slope of the baflles in one position. Therefore, an average of theangle of slope of the bafiles is preferably used for the angle of slopeof the side walls.

Naturally the slope of the side walls facilitates travel of sludgecollected on the baffles toward the bottom of the tank and into thesludge collection chamber 91. It is within this chamber that the sludgeconveying means '75 rotates to move the sludge to the outlet.

In addition to providing a rectangular settling tank which allows forsettling small particles at high over.- flow rates, this inventionprovides a settling tank which can be easily used in a multi-tanksystem. The basic multi-tank arrangement is shown schematically in Figure 5, and by referring to that figure, it will be noted that a commoncentral wall 16 may be used between two tanks.

In all of the embodiments of the invention presented in the drawings,the sludge outlet channel 99 and conveyor drive 79, 81 have been shownat the front of the tank 2, however, it should be apparent that thechannel or drive, or either or both, could be located adjacent the backend 50 of the tanks. This is one example of the ease with whichcomponents can be changed to different locations, and a definiteadvantage of the improved tank provided by this invention over thesettling tanks of the prior art.

Although multiple overflow launders have been illustrated in thedrawings, it should be apparent that a single overflow launder may beprovided if desired. Multiple launders insure uniform overflow, but incertain instances a single launder may be entirely adequate. In anycase, the launders should have adjustable extensions, such as thosedesignated by numeral 131 in Figure 2, so as to allow for control oroverflow level. Extensions 131 are coupled to the launders by screws 133as shown most clearly in Figure 10, but any suitable coupling means uwhich allows for adjustment may be used. The adjust-. ment of theoverflow controls the depth of the laminar flow as does the adjustmentof the height of the bafiies.

In order to allow for adjustment of settling rate, the vibrator 44 andmechanical means 36 which control baflic agitation should be adjustablein frequency as well as in magnitude. Vibrators are now manufacturedwith such adjustment, and if the pivot point of lever 37 is moved, themechanical means 36 (Figure 2) becomes adjustable in magnitude ofagitation.

After considering the foregoing description of the invention, theoperation of the tank should be apparent. Fluid sewage is introducedinto the tank and passed through distributors which provide a laminarnon-turbulent flow. Bafiies are disposed in the tank, and these bafilesintercept particles which settle from the carrier fluid. The baffles arereally inclined planes down which the settled particles slide afterinterception, and the invention provides for agitating the baffles orinclined planes to hasten movement of sludge toward the bottom of thetank. In addition, the invention provides for conveying the settledsludge to an outlet location. As part of the apparatus described herein,the incoming mixture of suspended solids and liquids is divided intostreams which oppose one another upon entrance into the tank, or whichoppose one another after being stopped and laterally dispersed.

The foregoing description will undoubtedly suggest many modifications tothose of ordinary skill in the art, and therefore, it is intended thatthe description be interpreted as illustrative and not in a limitingsense.

We claim:

1. A settling tank comprising an elongated containing means having abottom wall, side walls and end walls, fluid inlet means and fluidoutlet means communicating with opposite ends of the interior of saidtank, a fluid inlet channel communicating with said fluid inlet means, aseries of fluid distributors communicating with said fluid inletchannel, said fluid distributors comprising means for directing fluidsin opposing directions whereby the fluid entering said tank through saiddistributors assumes a substantially non-turbulent laminar flow, aplurality of baflies disposed in said tank over which fluid exiting fromsaid distributors passes. said baffles having top and bottom ends andbeing inclined with the bottom ends closer to said distributors than thetop ends, a collection chamber located below the bottom ends of saidbaflles for collecting settled solids, an outlet chamber, and submergedconveying means for transporting settled materials from said collectionchamber to said outlet chamber.

2. A settling tank as defined in claim 1, wherein said means fordirecting fluids in opposing directions comprises a series of T-shapetubes.

3. A settling tank as defined in claim 2 and further including means toagitate said baflles.

4. A settling tank as defined in claim 3 wherein said conveying meanscomprises a spiral conveyor, and wh rein said conveyor is disposedsubstantially parallel with the bottom wall of said containing means.

5. A settling tank as defined in claim 4 wherein said baffles aremoveably mounted within said tank, and wherein said tank furtherincludes means for adjusting the level of said battles with respect tothe top liquid level of said tank.

6. A settling tank as defined in claim 4, and further including overflowmeans disposed near the fluid outlet means.

7. A settling tank as dcfined'in claim 1 wherein said means fordirecting fluids in opposing directions comprises a series of tubularoutlets and a series of deflection plates disposed in alignment withsaid tubular outlets.

A settling tank as defined in claim 7 and further including means toagitate said baffles and means to change the level of the top ends ofsaid baffles with respect to the top liquid level in said containingmeans.

,9. A settling tank as defined in claim 8 wherein said conveying meanscomprises a spiral sludge conveyor.

10. A settling tank as defined in claim 1 and further including means toagitate said baflles.

11. A settling tank as defined in claim 10 wherein said means foragitating said baffles comprises a reciprocal rod and mechanical meansfor reciprocating said rod.

12. A settling tank asdefined in claim 10 wherein said means foragitating said bafiies comprises a vibrating means directly coupled withsaid baflles.

13. A settling tank as defined in claim 12 wherein said baflfles arecoupled to said vibrating means by means of a frame, and wherein saidframe is adapted to support said bafiles within said containing means.

14. A settling tank as defined in claim 1 wherein said fluiddistributions are disposed at least substantially in alignment with thetop of said bafiies.

References Cited in the file of this patent UNITED STATES PATENTS2,678,730 Coulter May 18, 1954 2,688,402 Butterworth Sept. 7, 1954 102,702,124 Stengel Feb. 15, 1955 FOREIGN PATENTS 10,557 Great Britain1908

